import java.util.Stack;

class MyQueue {

    private Stack<Integer> s1;
    private Stack<Integer> s2;

    public MyQueue() {
        s1 = new Stack<>();
        s2 = new Stack<>();
    }
    
    public void push(int x) {
        s1.push(x);
    }
    
    public int pop() {
        if(!s2.empty()) {
            return s2.pop();
        }else {
            while(!s1.empty()) {
                int val = s1.pop();
                s2.push(val);
            }
            return s2.pop();
        }
    }
    
    public int peek() {
        if(!s2.empty()) {
            return s2.peek();
        }else {
            while(!s1.empty()) {
                int val = s1.pop();
                s2.push(val);
            }
            return s2.peek();
        }
    }
    
    public boolean empty() {
        return s1.empty() && s2.empty();
    }
}